IAC Runs Continuously, Other Battery Drain Issues
 

HELP!


Hello all. I have '94 850/216K miles, been in the family since birth and Volvo dealers have done an estimated 99% of ALL maintenance work.


After correcting an intermittent engine shut-down issue by replacing the Camshaft Position Sensor, the IAC valve now runs continuously. Additionally, something else is draining the battery, although slower, when the car is dormant. I did the standard troubleshooting with my trusty multimeter and found a 1.4 amp draw with the IAC valve plugged in and it drops to .5-.6 amp draw when I unplug it. I've pulled every fuse individually trying to isolate the system with no change in those results.


Next, I had the battery tested, I've tried a different IAC valve, replaced the Throttle Position Sensor, replaced the ECU (though with another used one), replaced the Ignition Switch, and replaced the Coolant Temperature Sensor (and thermostat).


This one is killing me. The car runs great when running and still looks good for her age so I really don't want to give up on it. However, it's getting pretty old disconnecting the battery every time it's going to sit for more than 12 hours. Any ideas about what I can try next? Or has anyone run into similar issues?


Thanks for reading!

Sounds like something in the ECU world is staying powered. Maybe a relay is stuck.

The wiring diagrams for these cars are hard as heck to read; they're at volvowiringdiagrams.com

Without looking for what all relays might power something in that system, I will just mention one that I know of. The relay mounted on top of the radiator is one of them. It has that plug that rots internally and goes wrong. You may have some wires touching each other inside that plug. It's easy to get to also. There may be others, that is just one that I am aware of because it causes me a lot of trouble.

Thank you for the quick reply. I read about those on another forum a few months ago researching some other issue and remember thinking mine are in pretty rough shape. I'm on it.

Thanks again!

firebirdparts was spot-on
 

Thanks very much, Firebirdparts, your suggestion was spot on. In my case, it was the "starter relay" (as some have called it)... it is the large grey relay driver-side on top of the radiator. I pulled the old one while everything was still connected, the IAC valve stopped running (as expected), plugged the new ($22.95+ free shipping on eBay from eEuroparts.com) one in, and the IAC remained dormant. A quick voltage check and I was back to my normal 20 milliampere draw. A turn of the key to the 3rd position and the IAC started humming away again.


So jazzed right now I cant even tell you.


Thanks again!